Thuban
Where is Thuban?
Look northwest, about 44° up at 20:20 in Draco.
- Rises
- Always up
- Highest
- 14:08
- Sets
- Never
- Best after dark
- 20:20 · 44°
Can I see Thuban tonight?
From London tonight, Thuban is above the horizon all night. It’s highest soon after dark, around 20:20, in the northwest at 44°.
At magnitude 3.6 it is visible by eye, even from many towns, when the sky is clear.
This is position and timing only: clouds, haze and light pollution aren’t included.
What does Thuban look like?
Thuban looks blue-white to the eye (color is easier to see in binoculars). Its spectral type is A0III: white giant (hotter than the Sun).
Eyes
A modest star between the Big Dipper’s handle and the Little Dipper’s bowl.
Binoculars
A white point in a dim area.
Telescope
A single point of light.
About Thuban
Thuban, in Draco the Dragon, was the North Star nearly 5,000 years ago, when the pyramids of Egypt were being built. Earth’s slowly wobbling axis has since moved the pole closer to Polaris.
It is a white giant star about 300 light-years away and not very bright today, which surprises people who expect a former pole star to stand out.
Thuban was closest to the pole around 2800 BC. It has been suggested that one of the narrow shafts of the Great Pyramid pointed toward it, though that idea is debated.
Despite carrying the label Alpha Draconis, Thuban is not the brightest star in Draco. Eltanin, in the Dragon’s head, is brighter.
Thuban is a close binary, with two stars orbiting each other about every 51 days.
Because the pole’s slow circle repeats about every 26,000 years, Thuban will be near the pole again about 21,000 years from now.
Thuban in Draco
Questions
Why isn’t Thuban the North Star anymore?
Sources: SkyMate; Wikidata (CC0). Positions computed for your place and time with astronomy-engine. Data & Licences